ARS | Publication request: The Capacity and Efficiency of Official Grade Shellers

Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 5, 2005
Publication Date: August 15, 2006
Citation: Lamb, M.C., Blankenship, P. 2006. The capacity and efficiency of official grade shellers. Peanut Science. 33:12-18.

Interpretive Summary: The US peanut industry is interested in raising the allowable peanut moisture content for marketing of farmerstock peanuts. It is imperative that the change not significantly increase time for official grading during harvest. USDA has not allowed raising the peanut moisture content (MC) maximum because of concern that the sheller used in official grading would not provide appropriate capacity or efficiency to meet time constraints for shelling peanuts at higher MC. Subsamples of runner type, farmer stock peanuts were shelled and the efficiency and capacity of the official grade sheller evaluated. Usually pods falling into the catch pan during shelling are recycled through sheller compartments to reduce hand shelling. Peanuts were shelled either with9 or without pod recycling shelling. Variance in pod count after shelling was not explained by moisture content in linear regressions of pods after shelling with or without recycling. Comparisons were conducted separating data into shelling with and without pod recycling and into three levels of kernel MC. Peanuts for the highest moisture level shelled with pod recycling had after shelling pods and pod weights significantly higher than other moisture levels. This study indicates that the allowable MC maximum for grading runner type peanuts can be raised without increasing shelling time for official grades.

Technical Abstract: Some segments of the US peanut industry are interested in raising the allowable peanut grading moisture content (MC) at farmer marketing from 10.49% to 18.49%. USDA has not allowed raising the MC maximum because of concern that the sheller used in official grading would not provide appropriate capacity or efficiency to meet time constraints for shelling peanuts at higher MC. To evaluate efficiency of the grade sheller, a total of 112, 500.9 g subsamples of runner type, farmer stock peanuts with varying moisture contents were shelled. Kernel MC averaged 16.7% ranging from 7.7% to 37.4% and SD of 7.8%. Peanuts were shelled either with or without pod recycling during shelling. Variance in pod count after shelling was not explained by MC in linear regressions of pods with recycling during shelling (R2 = 0.26) and without recycling during shelling (R2 = 0.02). After shelling pod weight means had comparable trends as pod count means. Comparisons were conducted separating data into shelling with and without pod recycling and into three levels of kernel MC including: < 10.49% (MC1); > 10.49%, < 18.49% (MC2); and > 18.49% (MC3). MC3 level peanuts shelled with pod recycling had an average of 38.1 pods after shelling which was significantly higher than all other MC levels (P = 0.05). Comparing data by MC1, MC2, and MC3 levels showed that shelling peanuts for four minutes up to 18.49% MC would not significantly increase after shelling pod count or weight compared to shelling with MC < 10.49%.